'for..in' is used instead of 'for..of'

Reports a usage of a <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/for...in">for..in</a> loop on an array. Suggests replacing it with a <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/for...of">for..of</a> loop.

for..of loops, which are introduced in ECMAScript 6, iterate over iterable objects. For arrays, this structure is preferable to for..in, because it works only with array values but not with array object's properties.